Evaporator, especially for a waste gas heat recovery device

ABSTRACT

An evaporator ( 1 ) for a waste heat recovery device includes a plurality of evaporation devices ( 2 ) for the flow of a fluid. The evaporation devices ( 2 ) are arranged in a stack-line manner in a stacking direction (S). A plurality of rib structures ( 3 ) are designed and arranged for the flow of a gas through them, in a gas flow direction (G). Each evaporation device ( 2 ) has a pair of plates ( 4 ). The first and second evaporator plates ( 5, 6 ) are mutually complementary with one another and have a meandering evaporation channel ( 9 ) each on a respective inner side ( 7, 8 ). The inner sides ( 7, 8 ) of the first and second evaporator plate ( 5, 6 ) are in flat contact with one another in a mounted state outside the evaporation channel ( 9 ). Adjacent pairs of plates ( 4 ) are supported with their respective outer sides ( 16, 17 ) on the rib structure ( 3 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application 10 2012 202 361.5 filed Feb. 16, 2012, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to an evaporator, especially for a waste heat recovery device.

BACKGROUND OF THE INVENTION

Evaporators, by means of which the working medium of the closed cycle can be evaporated, while the heat needed for this is removed from the waste gas of an internal combustion engine, are used in waste heat recovery devices that are based on the principle of a Rankine cycle or a Rankine-Clausius cycle. Such an evaporator correspondingly contains a gas path for the waste gas, on the one hand, and an evaporation path for the working medium to be evaporated, on the other hand.

Such an evaporator may be designed, for example, as a plate heat exchanger and correspondingly have a plurality of channel plate arrays, which are stacked in a stacking direction, wherein a gas path is formed between two adjacent channel plate arrays each, and a gas, by means of which the heat needed for the evaporation of the liquid can be fed, can be sent through said gas path. The corresponding channel plate array may preferably contain a liquid inlet, a steam outlet and a channel connecting the liquid inlet with the steam outlet, said channel forming, for example, a multiply deflected evaporation path for the liquid to be evaporated.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved embodiment for an evaporator of the type mentioned in the introduction or for a waste heat recovery device equipped therewith.

The evaporator according to the present invention comprises a plurality of evaporation devices for the flow of a fluid, which are arranged one on top of another in a stack-like manner in a stacking direction, and a plurality of rib structures, which are designed for the flow of a gas through them in a gas flow direction. Each evaporation device has a pair of plates with a first evaporator plate and a second evaporator plate. The first and second evaporator plates, which have a mutually complementary design, have a meandering evaporation channel on a respective inner side. The inner sides of the first and second evaporator plates are in flat contact with one another in an area outside of the area of the evaporation channel, in a mounted state. Adjacent pairs of plates being supported by their outer sides on such a rib structure.

It is possible by means of the rib structures provided for supporting adjacent pairs of plates to manufacture the pairs of plates with a very small material thickness and yet ensure a necessary mechanical stability of the evaporator according to the present invention, especially in respect to the mechanical stiffness thereof. At the same time, an especially intense thermal interaction can be achieved between the rib structures through which a gas flows and the evaporation devices through a fluid flows due to the small material thickness of the pairs of plates.

A preferred dimension for the thickness of the first and second evaporator plates may be preferably between 0.2 mm and 0.5 mm and at most preferably approximately 0.4 mm.

In a preferred embodiment, the rib structure is arranged in a sandwich-like pattern between two adjacent pairs of plates. This makes it possible to manufacture a mechanically especially stable, but also highly compact evaporator.

The direction of gas flow is preferably at right angles to the stacking direction. The provision of a large number of rib structures can nevertheless be combined with a highly compact design in this manner.

In one embodiment variant, it is conceivable that the evaporation channel has a plurality of main flow sections, which extend at right angles in respect to both the stacking direction and the gas flow direction, wherein adjacent main flow sections are fluidically connected with one another by means of connection sections extending in the gas flow direction. A crossed counterflow principle, which makes possible an especially good thermal interaction of the gas with the fluid, can be obtained in this manner for the evaporator concerning the flow of a fluid through the evaporation devices and the flow of gas through the rib structures.

In one embodiment, which likewise represents a variant, the evaporation channel has an essentially flat flow cross section for the purpose of a very compact design. “Flat” means here that an effective width of the evaporation channel in the flow cross section is substantially greater than a height of the evaporation channel, which is defined by a direction directed at right angles to a plane defined by the evaporator plates. The width of the evaporation channel may be especially 4 times, 6 times, 8 times or 10 times the height. Such a flat design of the evaporation channel also brings about a pronounced interaction of the gas flowing through the rib structures with the fluid flowing through the evaporation devices, which facilitates the evaporation thereof.

In an especially preferred embodiment, the rib structure comprises a plurality of rows of ribs arranged next to each other in relation to the gas flow direction and are corrugated and especially corrugated in a rectangular manner. The efficiency of the thermal interaction can be further increased on the gas side by means of such rows of ribs.

It is conceivable in one embodiment variant that each row of ribs consists of elevations and depressions alternating following each other, which are each connected with one another by means of webs, with rows of ribs that are adjacent to each other in relation to the gas flow direction being arranged offset in relation to one another in relation to the positions of elevations and depressions. An especially space-saving technical embodiment of the rib structures is possible in this manner.

In an especially preferred embodiment, each evaporation device has an inlet area each with an inlet opening and an outlet area with an outlet opening for the inlet and outlet of the fluid, where adjacent inlet openings are in fluidic connection with one another and adjacent outlet openings are in fluidic connection with one another in a mounted state of the evaporator.

In one embodiment variant, the inlet opening and the outlet opening are designed each as an inlet dome and outlet dome provided on the outer side of the first and second evaporator plates. Despite such a space-saving design, this ensures a large flow cross-section of the inlet and outlet openings for the fluid flowing through the evaporation devices.

The inlet dome and outlet dome preferably have each an essentially ring-shaped cover surface. Adjacent evaporator plates can be fastened to one another in a simple manner, especially by soldering, by means of such a cover surface.

In one embodiment of an especially compact design, the inlet dome and the outlet dome each taper conically in the direction of the adjacent evaporation devices.

For the purpose of feeding fluid into the evaporation devices of the evaporator in a space-saving manner, the evaporator may have, in one embodiment variant, a fluid inlet opening and a fluid outlet opening, which are fluidically connected each with the inlet openings and outlet openings of the evaporation devices, respectively, said fluid inlet opening and said fluid outlet opening being arranged in the direction of gas flow.

The evaporator may, furthermore, preferably have a feeding line of a funnel-shaped design for feeding the gas into the rib structures and/or a drain line of a funnel-shaped design for removing the gas from the rib structures.

It is conceivable in one embodiment variant that the evaporator comprises a housing for fluidically limiting a gas path of the gas flowing through the plurality of rib structures. It is thus unnecessary to provide an outer fluidic limitation of the rib structures, which reduces the total number of components needed for the evaporator.

The first and second evaporator plates may be soldered to one another in a mounted state, especially by means of Ni-based solders, in an embodiment that can be manufactured in an especially simple manner.

The rows of ribs may be made of steel, preferably stainless steel, for the purpose of providing an especially stable embodiment.

Further important features of the present invention appear from the subclaims, from the drawings and from the corresponding description of the figures on the basis of the drawings.

It is apparent that the above-mentioned features, which will also be explained below, can be used not only in the particular combination indicated, but in other combinations or alone as well without going beyond the scope of the present invention.

Preferred embodiments of the present invention are shown in the drawings and will be explained in more detail below, with identical reference numbers relating to identical or similar or functionally identical components. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic exploded isometric view of an evaporator according to the present invention;

FIG. 2 is a schematic isometric view of an evaporation device of the evaporator in a non-mounted state;

FIG. 3 is a schematic isometric view showing a plurality of evaporation devices of the evaporator in a mounted state;

FIG. 4 is side view showing an inlet dome of an evaporation device;

FIG. 5 is a schematic isometric view of a rib structure of the evaporator;

FIG. 6 is a longitudinal sectional view showing the evaporator according to FIG. 1; and

FIG. 7 is a schematic isometric view of the mounted evaporator according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, the evaporator according to the present invention, which may preferably be designed according to the cross counterflow principle, is designated by 1 in FIG. 1. The different components of the evaporator 1 are shown at spaced locations from one another (exploded) in the view in FIG. 1 in order to improve the possibility of representation.

Evaporator 1 comprises a plurality of evaporation devices 2 for the flow of a fluid, which are arranged one on top of another in a stack-like manner, and a plurality of rib structures 3, which are intended for the flow of a gas through them in a gas flow direction G. Gas flow direction G extends at right angles to the stacking direction S. Each evaporation device 2 has a pair of plates 4 with first and second evaporator plates 5, 6.

Such a pair of plates 4 with first and second evaporator plates 5, 6 is shown in FIG. 2 as an example in a non-mounted state. The first and second evaporator plates 5, 6 have mutually complementary designs and have a meandering evaporation channel 9 on a respective inner side 7, 8. In a mounted state, not shown in FIG. 2, the inner sides 7, 8 of the first and second evaporator plates are in flat contact with one another in an area outside of an area of the evaporation channel 9.

Evaporation channel 9 may have a plurality of main flow sections 10, which extend in a direction at right angles O in relation to both the stacking direction S and the gas flow direction G. Adjacent main flow sections 10 may be fluidically connected with one another by means of connection sections 11 each extending in the gas flow direction G.

Evaporation channel 9 may have an essentially flat design. “Flat” is defined here such that an effective width B of the evaporation channel is substantially greater in relation to a flow cross section than a height H of evaporation channel 9, which is defined by a direction extending at right angles to a plane defined by the evaporator plates. This is shown schematically in a schematic diagram supplementing FIG. 2 by reference number 40. This schematic diagram shows a flow cross section of evaporation channel 9. Width B of evaporation channel 9 maybe, in respective alternative variants, especially 4 times, 6 times, 8 times or 10 times the height H. A large flow cross section can be combined in this manner with a large effective interaction surface (between fluid and gas) and with a compact design.

Each evaporation device 2 may have an inlet area 12 with an inlet opening 14 and an outlet area 13 with an outlet opening 15 for the inlet and outlet of a fluid. Adjacent inlet openings 14 may be in fluidic connection with one another in a mounted state of the evaporation devices 2, and adjacent outlet openings 15 may correspondingly also be in fluidic connection with one another. This becomes clear especially from the view in FIG. 3, which shows a plurality of pairs of plates 4 with a plurality of inlet openings 14 in a mounted state.

Both inlet opening 14 and outlet opening 15 may be designed each as a respective inlet dome 18 and outlet dome 19 provided on an outer side 16, 17 of the first and second evaporator plates 5, 6.

FIG. 4 shows as an example such an inlet dome 18 in a side view. Both inlet dome 18 and the outlet dome may taper conically in the direction of the adjacent evaporation devices. A taper angle may be between approximately 40° and 60° and preferably approximately 50°.

As can be determined from the view in FIG. 2, inlet dome 18 and outlet dome 19 may have an essentially ring-shaped cover surface 20, 21 each. Especially good soldering of adjacent inlet and outlet domes 18, 19, for example, by means of an Ni-based solder, is possible in this manner.

FIG. 5 shows a rib structure 3 according to the present invention. Rib structure 3 comprises here a plurality of rows of ribs 22 arranged next to each other and in a rectangularly corrugated manner in relation to the gas flow direction G. Rows of ribs 22 may be manufactured from steel, preferably from stainless steel. Each row of ribs 22 consists of elevations 23 and depressions 24 alternatingly following each other, which are connected with one another via webs 25. Adjacent rows of ribs 22 are arranged offset in relation to one another in relation to the positions of elevations 23 and depressions 24. Improved thermal interaction can be achieved in this manner between rib structures 3 and evaporation devices 2.

Based on the view in FIG. 1, the arrangement of the rib structures 3 relative to the evaporation devices 2 will be explained below. Accordingly to this view, each rib structure 3 is arranged in a sandwich-like pattern between two adjacent pairs of plates 4, Adjacent pairs of plates 4 are supported according to the present invention with their respective outer sides 16, 17 (cf. FIG. 2) on a rib structure 3.

Evaporator 1 may comprise, furthermore, a housing 26 for fluidically limiting a gas path of the gas flowing through the plurality of rib structures 3. It is thus unnecessary to provide an outer fluidic limitation of the rib structures 3 separately.

Evaporator 1 may have, furthermore, a feeding line 27 of a funnel-shaped design (cf. FIG. 1) for feeding the gas into the rib structures 3 and a drain line 28 of a funnel-shaped design for removing the gas from the rib structures 3. It is clear that other geometries are also conceivable in variants concerning the design of feed line 27 and drain line 28.

FIG. 6 shows an evaporator 1 according to the present invention in a longitudinal sectional view. It becomes clear from this view that evaporator 1 can have a fluid inlet opening 29 and a fluid outlet opening 30, which are fluidically connected with the inlet openings 14 and outlet openings 15 of the evaporation devices 2, respectively. Fluid inlet opening 29 and fluid outlet opening 30 are preferably arranged in the gas flow direction G. A gas stream, especially of a waste gas, is designated by arrows with the references number 31 in FIG. 1.

Finally, FIG. 7 shows a perspective view of an evaporator 1 in a mounted state.

The mode of operation of evaporator 1 will be explained below in reference to the drawings explained above. A hot gas, especially a waste gas, for example, from an internal combustion engine of a motor vehicle, can enter in the direction of the gas flow direction G in the rib structures 3 of the evaporation devices 2 and thus reaches the rows of ribs 22. Since adjacent pairs of plates 4 of the evaporation device 2 are supported at the rib structures 3, strong thermal interaction of the rib structures 3 with the evaporation devices 2 is ensured. Consequently, strong thermal interaction of a gas flowing through the rib structures 3 can also take place with a fluid flowing through the evaporation channels 9 of the evaporation devices 2. By means of such a thermal interaction, the hot gas can be cooled very effectively by means of such a thermal interaction before discharge from the rib structure 3 while the fluid flowing through the evaporation devices 2 evaporates.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 

What is claimed is:
 1. An evaporator for a waste heat recovery device, the evaporator comprising: a plurality of evaporation devices for the flow of a fluid, the evaporation devices being arranged in a stack-like manner in a stacking direction; and a plurality of rib structures for the flow of a gas in a gas flow direction, wherein: each of the evaporation devices comprise a pair of plates with a first evaporator plate and with a second evaporator plate; the first evaporator plates and the second evaporator plates are mutually complementary to one another and each have a meandering evaporation channel on a respective inner side; the first evaporator plates and the second evaporator plates are in flat contact with one another in a mounted state outside of an area of the evaporation channel; and adjacent pairs of plates are supported at outer sides on an adjacent one of the rib structures.
 2. An evaporator in accordance with claim 1, wherein each rib structure is arranged in a sandwich-like pattern between two adjacent pairs of plates.
 3. An evaporator in accordance with claim 1, wherein the gas flow direction extends at right angles to the stacking direction.
 4. An evaporator in accordance with claim 1, wherein: each evaporation channel has a plurality of main flow sections, which extend in a direction at right angles in relation to both the stacking direction and the gas flow direction; and the main flow sections that are adjacent are fluidically connected with one another by means of connection sections extending in the gas flow direction.
 5. An evaporator in accordance with claim 1, wherein each evaporation channel is essentially flat.
 6. An evaporator in accordance with claim 1, wherein each rib structure comprises a plurality of rows of ribs arranged next to each other in relation to the gas flow direction and in a corrugated.
 7. An evaporator in accordance with claim 6, wherein: each row of ribs comprises elevations and depressions following each other alternatingly, which are connected with one another by means of respective webs; and rows of ribs that are adjacent to each other in relation of the gas flow direction are offset in relation to one another in relation to a position of elevations and depressions.
 8. An evaporator in accordance with claim 1, wherein: each evaporation device has an inlet area with an inlet opening and an outlet area with an outlet opening for the inlet and outlet of the fluid; and adjacent inlet openings are in fluidic connection with one another and adjacent outlet openings are in fluidic connection with one another in a mounted state of evaporator.
 9. An evaporator in accordance with claim 8, wherein each inlet opening comprises an inlet dome on an outer side of one of the first evaporator plates and second evaporator plates and each outlet opening comprises an outlet on an outer side of one of the first evaporator plates and second evaporator plates.
 10. An evaporator in accordance with claim 9, wherein each inlet dome and each outlet dome has an essentially ring-shaped cover surface.
 11. An evaporator in accordance with claim 8, further comprising: an evaporator fluid inlet opening; and an evaporator fluid outlet opening, wherein; the evaporator fluid inlet opening and the evaporator fluid outlet opening are in fluidic connection with the inlet openings and the outlet openings of the evaporation devices; and the evaporator fluid inlet opening and the evaporator fluid outlet opening are arranged in the gas flow direction.
 12. An evaporator in accordance with claim 1, further comprising at least one of: a feeding line of a funnel-shaped design for feeding gas into the rib structures; and a drain line of a funnel-shaped design for removing gas from the rib structures.
 13. An evaporator in accordance with claim 1, further comprising: a housing for a fluidic limitation of a gas path of gas flowing through the plurality of rib structures.
 14. An evaporator in accordance with claim 1, wherein the first and second evaporator plates are soldered to one another in a mounted state.
 15. An evaporator in accordance with claim 6, wherein the rows of ribs are manufactured from steel.
 16. An evaporator for a waste heat recovery device, the evaporator comprising: a plurality of evaporation devices for the flow of a fluid, the evaporation devices being arranged adjacent to each other to form a stack in a stacking direction, each evaporation device comprising a pair of plates, each pair of plates comprising a first evaporator plate and a second evaporator plate, the first evaporator plate having a shape that is essentially a mirror image of the shape of the second evaporator plate, each of the first evaporator plate and the second evaporator plate having a contact surface portion and a channel portion, wherein the first evaporator plate and the second evaporator plate are in flat contact with one another at the contact surface portion and the channel portion of the first evaporator plate and the channel portion of the second evaporator plate form an evaporation channel; and a plurality of rib structures for the flow of a gas in a gas flow direction, each evaporation device being supported at an outer side by an adjacent one of the rib structures.
 17. An evaporator in accordance with claim 16, wherein each rib structure is arranged in a sandwich-like pattern between adjacent evaporation devices.
 18. An evaporator in accordance with claim 16, wherein: each rib structure comprises a plurality of rows of ribs arranged next to each other in relation to the gas flow direction; and the gas flow direction extends at right angles to the stacking direction.
 19. An evaporator in accordance with claim 16, wherein: each evaporation device has an inlet area with an inlet opening and an outlet area with an outlet opening for the inlet and outlet of the fluid; adjacent inlet openings are in fluidic connection with one another and adjacent outlet openings are in fluidic connection with one another; each evaporation channel has a plurality of main flow sections, which extend in a direction at right angles in relation to both the stacking direction and the gas flow direction; each evaporation channel has a plurality of connection sections extending in the gas flow direction; the main flow sections that are adjacent to each other are fluidically connected with one another by the connection sections; and each channel portion is essentially flat.
 20. An evaporator in accordance with claim 19, further comprising: a housing for a fluidic limitation of a gas path of gas flowing through the plurality of rib structures; an evaporator fluid inlet opening; and an evaporator fluid outlet opening, wherein; the evaporator fluid inlet opening and the evaporator fluid outlet opening are in fluidic connection with the inlet openings and the outlet openings of the evaporation devices; and the evaporator fluid inlet opening and the evaporator fluid outlet opening are arranged in the gas flow direction. 